The present invention relates to a heat-processed food base, and particularly to a heat-processed food base which is useful for producing edible vessels having the form of a cone such as waffle cones, in which ices such as soft ice cream, ice cream or various other food materials are placed, i.e., waffle cones and square vessels called tarts, each of which is desired to have a small apparent specific gravity, porosity, light weight and a crisp taste.
Edible vessels which are filled with ices such as soft ice cream or ice cream and sold are generally formed in cone shapes by baking a batter obtained by kneading a mixture containing a basic ingredient such as wheat flour and a larger amount of water in a high-temperature heating plate by a manufacturer who specializes in producing such cones. These edible vessels are then packed and delivered to outlets for selling ice cream. However, since one merit of waffle cones are their very crispy taste, waffle cones involve many problems with respect to the difficulty of handling them during baking, as well as after baking and delivery to the sales outlets for ice cream, because waffle cones have very poor resistance to shock and are thus easily damaged.
To remove the aforementioned disadvantages, the present inventor previously proposed has a method of producing edible vessels, disclosed in Japanese Patent Application No. 26982/1984, in which water is added to a basic ingredient such as wheat flour in such an amount that the flour is formed into a dough and is kneaded, the thus-obtained mixture being spread to a given thickness, and the materials having a required shape then being obtained from the spread dough plate by wrapping or rolling it into cone shapes and hardening to cone shapes immediately after baking to obtain edible vessels.
However, in the above-described prior art, the former method has a problem in that, since cone-shaped edible vessels which are hardened immediately after baking are shipped, the cone-shaped edible vessels are easily damaged when shipped, for example, about 20 to 30% of the waffle cones shipped will be no good. In order to avoid this problem, the former method may be employed at the side of a user, i.e., the outlets of a soft ice cream distributer. However, this involves many problems. One is that the level of equipment investment for such items as a baking machine and an apparatus for preparing materials is increased, and there are sometimes limits on the space available for installing such equipment in sales outlets regardless of the difficulty of handling waffle cones and the technique of baking a material which is required, regardless of the amount of the material. It is also difficult to ensure that workers acquire the necessary technique for handling a baking machine and arrange for the supply of the required amperage of electric power when such equipment is installed at sales outlets where ice cream is sold, because they are often temporary employees or part-time workers. Thus, the former method cannot be readily employed in the outlets where ice cream is sold.
On the other hand, the latter method also involves many problems, for example, the fact that waffle cones having a crispy taste cannot be obtained.
The most important reason for the use of wheat flour as a confectionary ingredient is that wheat flour contains protein, unlike rice flour, potato flour and the flour of other grain, most of which consists of starch alone.
Starch is changed to an .alpha.-form by water and heat and plays a principal role in forming the shapes of various kinks of confectionary, as well as being an ingredient thereof. With respect to its suitability in the processing of confectionary, wheat flour has processing properties which are mainly determined by the protein contained therein, together with starch as a main component thereof, unlike other types of flour used as basic ingredients of confectionary such as rice flour and potato flour. The properties of wheat flour which are so different from the other types of flour used for confectionary are attributed to its protein component.
Wheat flour greatly differs from other basic ingredients for confectionary in the point that, when wheat flour is kneaded with water, the protein molecules contained therein absorb water, hydrate, and are bonded to each other to form a network structure consisting of sticky and elastic gluten. It could be said that the present invention is based on control of the water and heat used for changing starch to an .alpha.-form, as well as control and supervision of the employment of gluten, and clarification of its behavior.
Wheat flour is classified according to the properties and amounts of protein contained in it, i.e., strong flour, medium flour and weak flour. This classification is based on the amounts and properties of gluten produced by the protein, and the use of wheat flour depends upon these amounts and properties.
______________________________________ Class Protein content (%) Gluten Main use ______________________________________ Strong flour 12-14 Strong Bread, Chinese noodles Medium flour 8-11 Slightly Wheat vermicelli strong Weak flour 7-8 Weak Confectionary Tempura ______________________________________
In general, weak flour containing a small amount of protein is used in producing confectionary, and is kneaded with sugar, oil and fat, salt, eggs, milk, spices and coloring agents, together with water, to form a batter or dough which is then subjected to heat processing. In this heat processing, the starch contained in the wheat flour is changed to .alpha.-starch, and the protein which forms gluten is subjected to irreversible heat denaturation (heat coagulation) to provide foods in a digestible state with a good taste. General confectionary is basically produced by the above-described method, employing wheat flour as the main ingredient.
When wheat flour is kneaded with water, it immediately absorbs water, the amount of water absorbed by the starch being 30% of the weight thereof, and the amount of water absorbed by the protein being 200% of the weight thereof. The water, becomes chemically-bound water which causes the starch to solate and the protein molecules to be bonded together to form sticky and elastic gluten. The starch so produced starts to gel at about 54.degree. C. with the viscosity thereof being increased, and finally becomes .alpha. -starch which is edible and digestible. If heating is further continued, the .alpha.-starch is dehydrated to become solidified.
On the other hand, gluten forms a three-dimensional spongy network structure, leading to the formation of strong skeletons of the confectionary due to irreversible heat denaturation of the protein during heating.
Although hard confectionaries which are hard to masticate, such as crackers and hard biscuits, are produced in the aforementioned manner, porous foods which are finally supposed to have a crisp taste and to which the present invention relates may be produced by the method described below. A wheat flour ingredient is kneaded with water so that any bubbles produced in the kneaded batter are included in the network structure formed by the gluten due to the presence of egg or the edible surfactant consisting of a synthetic frothing emulsifier contained in the basic material. These bubbles included in the network structure make the gelled .alpha.-starch, which is a main component of the processing base material, porous as a result of the solidification which occurs due to the heat denaturation of the gluten upon heating. If heating is continued, the processing base material is dehydrated, and the starch is solidified to form a porous confectionary body. However, with respect to crispness, the body itself becomes hard, as a whole, due to the strong three-dimensional network structure formed by the gluten, even if it is porous.
Therefore, if an oil or fat is kneaded with the material base, the oil or fat is spread in a film form in the material base by the function of the above-described edible surfactant to prevent the binding of the network structure of gluten, whereby the end products can be provided with fragility crispness and a good taste.
Conventional confectionaries such as wafers and waffles which are characterized by crispness, fragility and a good taste can be obtained by heating the basic material until almost all the water therein has been released and further continuing the heating to a temperature above 200.degree. C.
Edible vessels for ice cream are generally formed into thin-skinned cones called waffle cones or dish-like shapes immediately after the products having fragility crispness and a good taste have been obtained by the above-described processing and before the products have cooled. Therefore, such vessels have very weak resistance to impact, and will be damaged during delivery to sales outlets where the vessels are filled with ice cream and sold, because the cones or dish-like forms of vessels are damaged when delivered to users, if each of them is not appropriately packed.